1. Field of the Invention
The invention relates to an electrowetting display technology and more particularly to an electrowetting display, a pixel array substrate thereof, and an electrowetting display pixel structure thereof.
2. Description of Related Art
FIG. 1 shows a top view and a partial cross-sectional view of a conventional electrowetting display. Referring to FIG. 1, an electrowetting display 10 includes a plurality of electrowetting display pixel structures 100. Each of the electrowetting display pixel structures 100 includes a pixel electrode 120 sandwiched between a substrate 10a and a substrate 10b, a hydrophobic insulating layer 130, an oily fluid medium 100a, an aqueous fluid medium 100b, and a wall 150. The hydrophobic insulating layer 130 is disposed on a surface of the pixel electrode 120. The wall 150 is disposed on the hydrophobic insulating layer 130. Moreover, the oily fluid medium 100a is disposed on a surface of the hydrophobic insulating layer 130, and the aqueous fluid medium 100b covers the oily fluid medium 100a. 
In FIG. 1, each of the electrowetting display pixel structures 100 is applied with a voltage. At this time, the oily fluid medium 100a is pressed against the wall 150 and the aqueous fluid medium 100b contacts with the hydrophobic insulating layer 130. Here, the oily fluid medium 100a and the hydrophobic insulating layer 130 contact at a location on the bottom left of each of the electrowetting display pixel structures 100. Generally, the oily fluid medium 100a is a colored hydrophobic fluid medium and the aqueous fluid medium 100b is a transparent aqueous fluid medium. Therefore, after passing through the oily fluid medium 100a, a light is absorbed by the oily fluid medium 100a, and the color of the oily fluid medium 100a is thus displayed. On the other hand, the light passes through the transparent aqueous fluid medium 100b so as to result in a grayscale variation during display.
Theoretically, each of the electrowetting display pixel structures 100 should have equal amounts of oily fluid medium 100a. As a consequence, when the electrowetting display pixel structures 100 are applied with the same voltage, each contact area of the oily fluid medium 100a and the hydrophobic insulating layer 130 of the electrowetting display pixel structures 100 is the same. In addition, the thicknesses of the oily fluid medium 100a of the electrowetting display pixel structures 100 are also the same. Practically, it is difficult to obtain oily fluid medium 100a with the same thickness by driving each of the electrowetting display pixel structures 100 with the same voltage. In the fabrication of the electrowetting display pixel structures 100, when the volume of the oily fluid medium 100a differs in each of the electrowetting display pixel structures 100 due to fabrication deviation, the adjustment of the thickness of the oily fluid medium 100a becomes more difficult.